I just bought the GSA Putt for our golf school at the PGA show. I'm sitting in the house now watching 5 PGA class A pros playing putting games with it and having a ball. Its greatly accurate, and we are using it with high speed video analysis equipment... its damn near perfect. You avid golfer this is a great tool. For $199 you cannot beat this device. I tested the Ping one, the swingbyte, the GSA is easier to use, has better online features, such as video to over lay, (the video isn't available to the public yet but will be soon and its just an update to the app), the storage and it will be a great teaching tool for my father.
The SAM is a great device... but its also $25,000.00... yes that's 25 GRAND... it provides more information then the normal non-engineer could ever need or use. Its far better then my TOMI, I highly recommend it.
PS... I have a TOMI Pro for sale, I bought it for $600 (PGA price) selling it with 2 cameras for $150!!! I no longer need it!